1. Field of the Invention
The invention concerns an x-ray tube of the type having a cathode to generate free electrons; an anode on which the free and accelerated electrons strike to cause x-ray radiation to be generated; a cooling channel with coolant flowing therethrough to cool the anode; a vacuum region between cathode and anode; and an exit window for allowing the x-ray radiation to exit from the x-ray tube.
2. Description of the Prior Art
An x-ray tube of this general type is known from United States Patent Application Publication 2006/015051 A1, for example. In this document an x-ray tube is disclosed in which a thin metal foil is used on which the electrons coming from a cathode (thus an electron source) strike with high energy and generate x-ray radiation that is directed out through a vacuum window. The thin cathode foil is cooled with the aid of a liquid. The foil is cooled on the back side, or the side facing away from the utilized radiation by a liquid conducted past the foil. A constriction in the cooling channel is present in the region of the cathode foil that leads to a higher flow speed of the liquid in this region so as to increase the effectiveness of the cooling. The quantity of generated bremsstrahlung is shifted relative to the generated characteristic radiation by this use of a very thin anode foil, such that an essentially monochromatic x-ray radiation arises in the range of the characteristic lines.
Although a relatively high degree of effectiveness is achieved in the generation of x-ray radiation in this embodiment of an x-ray tube, this is still not sufficient.